Golf ball manufacturers have been experimenting with various materials and manufacturing methods for golf balls over the years in an attempt to improve overall performance and durability and to further refine the manufacturing process.
For example, over the past years, golf ball manufacturers have been using ionomer resins for golf ball cover materials because of the durability, rebound, and scuff resistance characteristics of the materials. However, while ionomer resins are more durable than other types of golf ball layer materials, the same properties that result in durability also provide a hard “feel” and generally result in a lower spin rate and, thus, lower control, due to the hardness of the material.
Alternatively, polyurethane compositions produce “soft” covers and typically allow for greater control because of the increased spin. Because conventional polyurethane cover materials are typically formed of aromatic components, the ultraviolet degradation of the material, which leads to yellowing, led to the recent trend toward light stable cover materials, such as aliphatic polyurethane and polyurea materials. Whether aromatic or aliphatic in nature, however, the relative softness of the polyurethane and polyurea materials introduces durability issues. In addition, when the inner cover layer of a golf ball is formed from an ionomer resin and the outer cover layer is formed from polyurethane or polyurea, adhesion between the layers is an concern. In an effort to remedy potential delamination of the layers, the inner components of most commercially available polyurethane- or polyurea-covered golf balls are surface treated, e.g., corona discharge/silane dipping, to overcome the adhesion problems. The surface treatment, however, adds cost and time to the manufacturing process.
Further attempts to compensate for the “hard” feel of ionomer-covered golf balls and durability and adhesion issues with polyurethane-covered and polyurea-covered golf balls have resulted in blends of hard ionomer resins, i.e., resins with hardness values of about 60 Shore D and above, with relatively softer polymeric materials. For example, blends of hard ionomers with polyurethanes have been used to form intermediate layers and cover layers of golf balls. However, such blends generally have processing difficulties associated with their use in the production of golf balls due to the incompatibility of the components. In addition, golf balls produced from these incompatible mixtures will have inferior golf ball properties such as poor durability, cut resistance, and the like.
There are many similar examples of materials that have beneficial qualities to golf ball manufacturers, but, because of certain detrimental qualities, cannot be used independently of other more conventional materials. For example, a material with poor moisture resistance, poor durability, or low resiliency would not be useful on its own to form a layer of a golf ball. These type of materials are generally blended with other materials or not used at all.
Likewise, ceramic materials are recognized for their hardness and stiffness, however, these properties also make it difficult, if not possible, to achieve a shear and impact resistance level acceptable for use in golf balls. Organically modified silicates, also known as ceramers, have already been used with some success in polytetrafluoroethylene (PTFE) coating systems. The inclusion of ceramers in PTFE results in higher hardness and durability. Likewise, the use of a polar ceramer with fluoropolymers may increase adhesion to metals such as copper.
Thus, a need exists in the golf ball art to find a way to use materials typically discounted for golf ball layers in a way that capitalizes on the beneficial nature of the material while at the same time minimizing or completely overcoming the detrimental qualities. For example, it would be advantageous to form a golf ball layer or coating from a composition that incorporates ceramers or the like to take advantage of the beneficial properties of the ceramer while compensating for processing issues and brittleness associated with the material. In addition, golf balls having structural and/or coating layers formed, at least in part, from such compositions would be advantageous.